Chandra X-ray Images of Quasars
Observations of distant quasars in X-rays from Chandra (as seen in these images) and gamma-ray telescopes are helping scientists test the nature of space-time at extremely small scales.(Credit: NASA/CXC/FIT/E.Perlman et al)

Illustration of Quantum Foam
This artist's illustration depicts how the foamy structure of space-time may appear, showing tiny bubbles quadrillions of times smaller than the nucleus of an atom that are constantly fluctuating and last for only infinitesimal fractions of a second.(Credit: Illustration: NASA/CXC/M.Weiss)